Suction cups for civilian use are mainly for people to hang articles on a supporting surface such as walls. As it can be relocated to any positions at will, it can be conveniently used to hang towels, clothing articles, etc. Such suction cup is easy to use and can maintain attachment via vacuum assisted by adhesion, without drilling on the wall, it has therefore been widely used.
Existing suction cups may be made with or without a framework. Traditional suction cup without a framework is normally made of soft plastic integrally formed by injection molding. However, such suction cup cannot fully discharge air between the cup's adsorption surface and the supporting surface, and air may easily seep in via the edge of the adsorption surface, the adsorptive force is thus reduced and insufficient. The suction cup without a framework developed subsequently mainly consists of a fixing handle, a cup body, a cup cover placed on the cup body, a connecting rod provided at the center of the cup body, penetrating the cup cover and connecting to the fixing handle, and a spring loaded on the connecting rod. A force applied on the fixing handle pulls up the cup body via the connecting rod, so that vacuum (negative pressure) is generated between the cup body and the wall surface, thereby holding the suction cup onto the wall surface. However, this type of suction cup has a complicated structure and high production cost, it is not easy to operate, and its adsorptive force is not strong.
For conventional suction cups with a framework, the framework can transfer the pressing force very well, adsorptive force is thus greatly increased. Therefore, structural improvement of the suction cup with a framework has become the trend of R & D efforts of the industry.
At present, a conventional suction cup with a flat framework normally consists of a framework, a suction cup body covering the framework, a connecting rod on the back of the framework, a cup cover which is on the connecting rod and covers the back of the cup body, and a hanging hook provided on the back of the cup cover and connected to the connecting rod for pressing and pulling the framework. When fixing such suction cup on the wall surface, first put the suction cup on the wall surface, and then apply an external force to pull up the connecting rod and deform the framework (from the original flat form), creating a vacuum cavity between the suction cup body and the wall surface. At the same time, under the action of the external force, the cup cover transfers the force for counteracting on the cup body, limiting its deformation, preventing the external air from entering the vacuum cavity. Under such mutual counteraction, the cup body is sucked to the wall surface. The term “wall surface” means any supporting surfaces for hanging articles.
However, the adsorptive force of existing suction cup with a flat framework is not large enough, so that the suction cup may easily fall off from the wall surface, in particular when conditions of the wall surface are not ideal (for example, the wall surface is too smooth or has sags and crests), the friction force between the suction cup and the wall surface is too small, resulting in falling off of the suction cup. Thus, it cannot meet the need in terms of handing capacity and durability.